The present invention relates to a unique material suited for use in balloon catheters and, more particularly, to a low profile non-shortening wrapped balloon configured to expand to a predetermined diameter upon application of a predetermined pressure thereto. The unique properties of the material of the present invention enable wrapped balloons to be made without the use of internal bladders.
Balloon catheters are well known in the art. Such catheters are employed in a variety of medical procedures, including dilation of narrowed blood vessels, placement of stents and other implants, temporary occlusion of blood vessels, and other vascular uses.
In a typical application, the balloon is advanced to the desired location in the vascular system. The balloon is then pressure-expanded in accordance with a medical procedure. Thereafter, the pressure is removed from the balloon, allowing the balloon to contract and permit removal of the catheter. It is to be appreciated that prior art balloons are typically formed of an elastomeric material which is readily pressure-expanded, and also readily contracts upon removal of the inflation pressure.
Some catheter balloons constructed of both elastomeric and non-elastomeric materials have been described previously. U.S. Pat. No. 4,706,670 describes a balloon dilatation catheter constructed of a shaft made of an elastomeric tube and reinforced with longitudinal inelastic filaments. This device incorporates a movable portion of the shaft to enable the offset of the reduction in length of the balloon portion as the balloon is inflated. A major drawback to balloons of this type is the need for a bladder which increases the profile of the balloon.
Traditionally, a fluoropolymer matrix which is filled with a coating that does not extend outside the matrix permits the coating to pull away from the matrix causing holes that eventually demonstrate themselves in a “weeping” manner on the balloon. This is believed to be due to the inadequate adhesion strength between the matrix and the coating as well as the stress concentrations at those interfaces.
There is a need in the art for a low profile wrapped balloon which does not lengthen or shorten upon inflation and has the ability to withstand inflation pressure strain without disruption, while still remaining watertight without the use of a separate bladder that adds to the balloon profile. The present invention fulfills this need by providing a unique material which allows for the elimination of a bladder. It also allows the balloon to readily expand under pressure without leaking.